# Road trip gas cost calculator, per person Canonical URL: https://www.evenoutapp.com/tools/road-trip-gas-cost-calculator Updated: 2026-10-06 Divide the round-trip distance by your car's fuel efficiency to get the fuel used, multiply by the fuel price, add tolls and parking, then divide by the number of people. For 600 miles at 28 mpg with gas at $3.50 a gallon, $18 in tolls and 4 people, the trip costs $93.00 and each person pays $23.25. Key points: - Fuel cost = distance ÷ efficiency × fuel price. Add tolls and parking, then divide by everyone in the car. - The same sums work in kilometres and litres. If your car shows litres per 100 km, enter 100 ÷ that number as the efficiency. - Enter the full round-trip distance, and use the same unit of fuel for the efficiency and the price. - For an electric car, enter miles per kWh as the efficiency and the price of a kWh as the fuel price. ## When to use this calculator Use it before a trip to put a number on the shared driving costs, or after one to check that what people paid adds up. It covers the three costs that come with the car: fuel, tolls, and parking or anything else the group shares. Lodging, food and tickets are separate. The [trip cost per person calculator](https://www.evenoutapp.com/tools/trip-cost-per-person-calculator) adds those buckets together. For a daily commute with the same riders every week, the [carpool cost calculator](https://www.evenoutapp.com/tools/carpool-cost-calculator) is the better fit. ## How the cost is worked out Fuel is the only line that needs a calculation. Tolls and parking go in as totals. 1. **Fuel used** is the round-trip distance divided by the fuel efficiency. 2. **Fuel cost** is the fuel used times the fuel price. 3. **Trip cost** is the fuel cost plus tolls plus parking and other. 4. **Cost per person** is the trip cost divided by the number of people sharing. The driver counts in the headcount unless the group has agreed that the driver rides free. If the driver does ride free, enter one fewer person and the others pay a bit more. ## A worked example in miles Say a group drives 600 miles round trip in a car that does 28 miles per gallon. Gas costs $3.50 a gallon, tolls come to $18, and four people share the cost, driver included. - Fuel used: 600 ÷ 28 = about 21.4 gallons. - Fuel cost: 600 ÷ 28 × $3.50 = $75.00 exactly. - Trip cost: $75.00 + $18.00 = $93.00. - Each person: $93.00 ÷ 4 = $23.25. Add $12 of parking and the trip cost becomes $105.00, so each person pays $26.25. Without the driver in the count, three riders would pay $31.00 each on the original $93.00. ## Kilometres and litres The unit does not matter as long as the three numbers match: miles with miles per gallon and a price per gallon, or kilometres with kilometres per litre and a price per litre. Many cars show litres per 100 km instead. Divide 100 by that figure to get kilometres per litre. A car that uses 8 litres per 100 km does 100 ÷ 8 = 12.5 km per litre. Take 960 km round trip at 12.5 km per litre with fuel at 1.80 a litre, 12 in tolls and three people. Fuel used is 960 ÷ 12.5 = 76.8 litres, fuel cost is 76.8 × 1.80 = 138.24, the trip costs 150.24 and each person pays 50.08. The calculator shows a dollar sign, but the arithmetic is the same in any currency. Watch the gallon. A US gallon is about 3.785 litres and a UK imperial gallon is about 4.546 litres. A car that does 40 miles per imperial gallon does about 33 miles per US gallon, so enter the efficiency and the price in the same kind of gallon. ## Electric cars The formula does not care what the fuel is. Enter miles per kWh as the efficiency and the price of a kWh as the fuel price. Say a car covers 3.5 miles per kWh and charging costs $0.20 per kWh: 600 ÷ 3.5 is about 171.4 kWh, and the cost comes to $34.29. A flat fee for a charging session goes in the parking and other box. ## Common mistakes - **Entering one way.** The distance box wants there and back. One way halves the fuel. - **Mixing units.** Miles per gallon with a price per litre gives a wrong answer with no warning. - **Using the brochure figure.** If the car has a trip computer, enter its average from similar driving instead of the number printed in a brochure. - **Expecting exact cents.** When the total does not divide evenly, some shares are a cent higher than the others. The box shows the higher amount. ## Recording it in EvenOut On the trip, add each fill-up to a Trip group in [EvenOut](https://www.evenoutapp.com/) as an expense with the Fuel category and Split equally. Someone who rides only part of the way can be tapped out of that fill-up. [How to split gas on a road trip](https://www.evenoutapp.com/guides/how-to-split-gas-on-a-road-trip) goes through the other ways to share it, and the [group trip expenses calculator](https://www.evenoutapp.com/tools/group-trip-expenses-calculator) works out who owes whom once everyone has paid something. ## Frequently asked questions ### Does this include wear on the car or insurance? No. It adds fuel, tolls and whatever you enter under parking and other. Wear, depreciation and insurance are not worked out. If the group wants to give the driver something toward them, agree a flat amount first and add it to the parking and other box so it is shared like any other cost. ### What if the way back takes a different route? Add the two distances together and enter the total as the round-trip distance, with the tolls for both directions in the tolls box. If the car's efficiency is very different on the two legs, run the calculator once per leg and add the two results. ### Which fuel price do I enter if we fill up at several stations? Enter the price you expect to pay on average. After the trip, divide the total spent on fuel by the total gallons or litres bought to get the real average, or skip the estimate and add up the receipts. ## Sources - [NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically](https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8)